Field of the Invention
The present invention relates to an image encoding apparatus, a method, and an imaging apparatus.
Description of the Related Art
In recent years, increases in the number of pixels and framerates have been seen in imaging apparatuses equipped with an imaging element such as a CMOS image sensor. In conjunction with this, amounts of image signal outputted per unit time from the imaging element have increased, and there is a demand for measures for expanding transmission path bandwidth for outputting an image signal and for reducing image signal transmission amounts without reducing the number of pixels.
Meanwhile, as a method of reducing image signal transmission amounts, a method in which the image signal is encoded and then compression processing is performed is known. For example, in Japanese Patent Laid-Open No. 2010-4514, a method in which compression processing is performed by a DPCM (Differential Pulse Code Modulation) encoding method is proposed. Regarding the DPCM encoding method, it is a method for performing compression by taking pixel differentials that takes advantage of the level of spatial correlation of an image, and it can be configured by a relatively simple circuit.
As a method of reading from an image capturing element in an imaging apparatus, there is a technique of simultaneously reading a pixel signal of a plurality of lines from a pixel array in which a plurality of pixels is arranged two-dimensionally. However, in the conventional technique, even in the reading out of a plurality of lines, encoding processing is simply performed in relation to each line as a one-dimensional array. It can be said that coding efficiency is impaired because the level of spatial correlation is not considered optimally in relation to a multiple line read out.